--whole-archive
For each archive mentioned on the command line after the --whole-archive option, include every object file in the archive in the link, rather than searching the
archive for the required object files. This is normally used to turn an archive file into a shared library, forcing every object to be included in the resulting
shared library. This option may be used more than once.
Two notes when using this option from gcc: First, gcc doesn’t know about this option, so you have to use -Wl,-whole-archive. Second, don’t forget to use
-Wl,-no-whole-archive after your list of archives, because gcc will add its own list of archives to your link and you may not want this flag to affect those as
well.